CN105354880A - Line laser scanning-based sand blasting robot automatic path generation method - Google Patents

Abstract

The invention discloses a line laser scanning-based sand blasting robot automatic path generation method. The method comprises the following steps: 1, workpiece data information obtaining: obtaining data information of scanning sampling points on the surface of a workpiece to be sand blasted by adopting a 2D laser scanning manner; 2, workpiece surface STL model establishment: establishing a to-be-sand blasted workpiece surface STL model through point cloud pre-processing; 3, curved surface division: extracting and utilizing the geometrical characteristics and topological characteristics of the workpiece surface STL model so as to divide the curved surface of the workpiece into a plurality of planes without cavities; and 4, sand blasting track generation: constructing a characteristic frame according to the workpiece surface STL model and generating sand blasting tracks by adopting a cut plane projection method.

Description

A kind of sand blasting machine people automatic path generation method based on line laser structured light

Technical field

The present invention relates to a kind of sand blasting machine people automatic path generation method, specifically, relate to a kind of sand blasting machine people automatic path generation method, particularly sand blasting machine people based on line laser structured light carry out sandblasting automatic path generation method to Unknown Model workpiece.

Background technology

Large-scale steel structure weldment, because product is bordering on tailor-made product, so the workpiece shapes of each processing is not identical; Need to carry out surface pretreatment, cleaning surface oxide layer.Current use steel sand and plumbous sand combine, and adopt the pressurized air of 0.8MPa to blow steel sand, throw to surface of the work at a high speed, realize the sandblasting work of effects on surface.Because the kinetic energy of sand is higher, be easy to during current artificial hand-held sand rifle cause the injury to personnel.Simultaneously owing to producing more dust in sandblasting procedures, also easily cause the sense of discomfort of the respiratory system of workman.The workpiece of process is comparatively large, and a process workpiece approximately needs 2 classes of times of 2 people at present, is badly in need of employing equipment and people is freed from the work of heavy danger.

Common robot system adopts the mode of teaching and off-line programing, for be standardized, the processing of the product of repeatability.For some client, belong to customization and nonstandardly to manufacture a product, batch is very little.Due to the know-how of operator and the restriction of job specification, client does not wish that the mode by teaching or off-line programing provides the operating path of robot yet.The planning of this operating path for robot proposes high requirement, meet the requirement of real-time of work, can not have too many preliminary work again.From situation about understanding at present, not having similar Engineering Projects to use for reference, is the problem in the comparatively forward position of current robot application, therefore has comparatively actual reference and demonstration meaning.

Current Vision Builder for Automated Inspection adopts visible light source usually, can be used for the comparison of the image procossing pre-entering fixed form, for non-standard, template cannot be pre-entered, therefore, realize detecting of workpiece according to this and cannot realize yet, the generation of machining path is not known where to begin especially.

Summary of the invention

Technical matters: technical matters to be solved by this invention is: a kind of sand blasting machine people automatic path generation method based on line laser structured light is provided, this generation method carries out modeling by line laser structured light to unknown work piece in sandblasting project, and then carries out the automatic generation in path according to model.

Technical scheme: for solving the problems of the technologies described above, the technical scheme that the embodiment of the present invention adopts is:

Based on a sand blasting machine people automatic path generation method for line laser structured light, this generation method comprises the following steps:

The first step: obtain workpiece data information: adopt 2D laser scanning methods to obtain the scanning sample point data information treating sandblasting surface of the work;

Second step: set up surface of the work STL model: by point cloud pretreatment, sets up and treats sandblasting surface of the work STL model;

3rd step: divide curved surface: extract and utilize geometric properties and the topological characteristic of surface of the work STL model, is divided into some not with empty plane by curve surface of workpiece;

4th step: generate sandblasting track: according to surface of the work STL model construction feature frame, adopts cutting planes projecting method, generates sandblasting track.

As preference, the described first step comprises the following steps:

Step 101): arrange sand-blast shop: be placed in the middle part of workshop by AGV dolly, 3 industrial 2D laser scanners are fixedly mounted on support respectively, and 3 industrial 2D laser scanners lay respectively at top and two sides of AGV dolly, to treat that sandblasting workpiece is placed on AGV dolly, treat that sandblasting workpiece and AGV dolly are synchronized with the movement with guide rail;

Step 102): system calibrating is calibrated: calibrated sensor pose and servomechanism installation systematic parameter at zero point by three-coordinates measuring machine, and completion system is demarcated;

Step 103): scanning workpiece, obtain data message: drive guide rail to move with known speed, simultaneously 3 2D laser scanners are treated sandblasting workpiece with setpoint frequency and are carried out scanning, sampling, guarantee treats that sandblasting workpiece is complete by laser sampling plane, and what record that 3 2D laser scanners collect take time as the laser measurement values data message of label.

As preference, described second step comprises the following steps:

Step 201) put cloud conversion and splicing: the reference frame setting up sand blasting machine people, by step 103) the laser measurement values data message that obtains, by the relative pose relation of time tag and sensor measurement polar coordinate system and reference frame, be converted to the cloud data under sand blasting machine people reference frame, and by all Point-clouds Registrations to together, obtain the part model be made up of cloud data under reference frame;

Step 202) some cloud filtering: for step 201) part model that obtains, carry out filtering process, obtain accurate workpiece point cloud model:

Step 203) some cloud smoothing processing: adopt moving least squares surfaces approximating method, for step 202) the accurate workpiece point cloud model that obtains, smoothing process, obtains level and smooth point cloud model;

Step 204) build STL model: adopt greedy projected triangle method to step 203) the level and smooth point cloud model that obtains processes, and generates the STL model of curve surface of workpiece.

As preference, described step 202) specifically comprise:

Step 2021) position of installing according to AGV dolly and range of movement, reject and treat the sample area that sandblasting workpiece is irrelevant, under obtaining sand blasting machine people reference frame, be with noisy workpiece point cloud model;

Step 2022) reject step 2021 by median filtering algorithm) workpiece point cloud model in noise spot: to step 2021) each data point p in the band noisy workpiece point cloud model that obtains _i, with p _ifor median window center, getting the median window length of side is w, then ask for intermediate value to the scan-data of the w × w in median window when time, when time, p _iremain unchanged; Wherein, δ represents median filter filtering threshold; Thus the accurate workpiece point cloud model under obtaining robot reference's coordinate system.

As preference, described step 203) specifically comprise:

Step 2031) by step 202) the point cloud model region gridding that obtains;

Step 2032) revise the coordinate of each net point: the range of influence size first determining net point, then determine the point (x being positioned at net point range of influence _i, y _i, z _i), I=1,2 ..., n, n to represent in net point range of influence the sum of point; Fitting function subsequently according to formula (1) draws revised net point coordinate:

Z=f (x, y)=p ^t(x, y) α (x, y) formula (1)

In formula, p (x, y)=[1, x, y] ^trepresent linear base, subscript T represents transposition, and α (x, y) represents coefficient vector, and α (x, y) is according to optimization method obtain minimal value to try to achieve;

Step 2033) connection network lattice point, form fitting surface: according to revised net point coordinate connection network lattice point, form fitting surface;

Step 2034) cloud is projected to step 2033) fitting surface on, obtain level and smooth point cloud model.

As preference, described step 204) specifically comprise:

Step 2041) appoint and get a plane, using step 203) the some cloud that obtains as original point cloud, project to this plane, obtain and the planar point cloud one to one of the point in original point cloud;

Step 2042) for step 2041) the planar point cloud that obtains, it is that a sample triangular plate is as initial surface that random selecting three points connect, adopt algorithm of region growing constantly to merge to expand surface boundary triangular plate, form complete triangle mesh curved surface;

Step 2043) according to the annexation of point cloud projection, adopt the Topology connection that back projection method is determined between each initial three-dimensional point, gained triangle gridding is rebuild the surface mesh model obtained;

Step 2044) by step 2043) the surface mesh model that generates stores according to stl file format standard, obtains the STL digital-to-analogue model of workpiece.

As preference, the 3rd described step comprises the following steps:

Step 301) segmentation of areal model point cloud: to step 203) the level and smooth point cloud model that obtains, adopt and split based on stochastic sampling conforming some cloud partitioning algorithm, setting parted pattern is areal model, and segmentation obtains the fitting parameter of one group of plane point set set be made up of surface of the work Different Plane point set and each plane point set;

Step 302) detect inner and outer boundary key point;

Step 303) simplify frontier point: to step 302) the key point sequence that obtains simplifies, extracts angle point as key point, reject non-angle point element in sequence, the boundary point sequence set be simplified;

Step 304) carry out STL semantic label: according to step 303) the boundary point sequence set of simplification that obtains is to step 2044) the STL digital-to-analogue model that generates carries out Region dividing, in STL digital-to-analogue model, mark the inner and outer boundary in sand region to be painted, realize the semantic label of STL digital-to-analogue model.

As preference, described step 302) specifically comprise: by step 301) each plane point set S of obtaining _iplane fitting parameters according to its correspondence is handled as follows:

Step 3021) projection of some cloud: by plane point set S _iin the plane that represents to fitting parameter of all spot projections in, obtain the agonic planar point cloud model of this plane point set;

Step 3022) detect inside and outside packet boundary: the inner and outer boundary key point arrangement set extracting some cloud: for the cloud data in each planar point cloud model, choose the minimum outsourcing polygon vertex of plane respectively as key point: be polygon outer boundary summit situation for key point, with planar process vector direction for top, with one group of clockwise key point sequence composition border key point; Be polygon inner boundary summit situation for key point, with planar process vector direction for top, with one group of counterclockwise key point sequence composition border key point.

As preference, the 4th described step comprises the following steps:

Step 401) extraction model information: the STL model generated according to the 3rd step, extracts triangular plate grid information;

Step 402) build bounding box: build a rectangular parallelepiped that the STL grid surface of workpiece can be included as bounding box, and create corresponding bounding box coordinate system, the initial point of bounding box coordinate system is in the geometric center of bounding box rectangular parallelepiped, and each coordinate axis is parallel with each limit of rectangular parallelepiped;

Step 403) choose sandblasting feature frame: STL grid surface is projected to the face perpendicular to each axle positive dirction of bounding box, calculates the area of each projection, and choose the feature frame of a maximum face of projected area as sandblasting;

Step 404) generate sandblasting characteristic curve: set sandblasting covering radius as r, the spacing of each for sandblasting path stroke is chosen as r/2, the distance between adjacent feature line, thus on characteristic face, generate the sandblasting characteristic curve be parallel to each other;

Step 405) generate sandblasting track: project at surface of the work along normal direction with characteristic curve, the curve intercepted is sandblasting stroke, is connected by adjacent sandblasting stroke, obtains final sandblasting track.

Beneficial effect: compared with prior art, the sand blasting machine people automatic path generation method of the embodiment of the present invention is carried out at line sweep surface of the work by low cost 2D laser sensor, to set up 3D digital-to-analogue accurately, automatically generate the movement locus of robot on this basis, abandon traditional artificial teach programming mode.The method and speed block low relative to traditional reverse-engineering cost, can be widely used in the surface sand-blasting process of the surface sand-blasting process, particularly short run of large-scale steel structure weldment (such as large-scale engineering machinery), multi items, non-standard product.Can apply and the field such as such as oil derrick process, Treatment of Metal Surface simultaneously, have broad application prospects and economic benefit.

Accompanying drawing explanation

Fig. 1 is the FB(flow block) of the embodiment of the present invention;

Fig. 2 is the layout of sand-blast shop in the embodiment of the present invention;

Fig. 3 is the FB(flow block) of the first step in the embodiment of the present invention;

Fig. 4 is the FB(flow block) of second step in the embodiment of the present invention;

Fig. 5 is greedy sciagraphy schematic diagram in the embodiment of the present invention;

Fig. 6 is the FB(flow block) of the 3rd step in the embodiment of the present invention;

Fig. 7 a is the organigram of bounding box in the embodiment of the present invention;

Fig. 7 b is embodiment of the present invention intermediate cam mesh flake schematic diagram;

Fig. 8 is feature frame and characteristic curve schematic diagram in the embodiment of the present invention;

Fig. 9 is the FB(flow block) of the 4th step in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the technical scheme of the embodiment of the present invention is described further.

As shown in Figure 1, a kind of sand blasting machine people automatic path generation method based on line laser structured light of the embodiment of the present invention, this generation method comprises the following steps:

The first step: obtain workpiece data information: adopt 2D laser scanning methods to obtain the scanning sample point data information treating sandblasting surface of the work;

Second step: set up surface of the work STL model: by point cloud pretreatment, sets up and treats sandblasting surface of the work STL model;

3rd step: divide curved surface: extract and utilize geometric properties and the topological characteristic of surface of the work STL model, is divided into some not with empty plane by curve surface of workpiece;

4th step: generate sandblasting track: according to surface of the work STL model construction feature frame, adopts cutting planes projecting method, generates sandblasting track.

As shown in Figure 3, the described first step comprises the following steps:

Step 101): arrange sand-blast shop: be placed in the middle part of workshop by automatic guided vehicle (being called for short in literary composition: AGV) dolly, 3 industrial 2D laser scanners are fixedly mounted on support respectively, and 3 industrial 2D laser scanners lay respectively at top and two sides of AGV dolly, to treat that sandblasting workpiece is placed on AGV dolly, treat that sandblasting workpiece and AGV dolly are synchronized with the movement with guide rail; As shown in Figure 2, consider that 2D laser scanning surface can only obtain two-dimensional distance information, in order to obtain the complete sample information of workpiece, 3 2D laser scanners are placed in respectively top and the side of AGV dolly, and ensure that 3 2D laser scanning regions are coplanar, sandblasting workpiece is placed on AGV dolly and moves with known speed with guide rail, and 3 2D laser scanners carry out scanning sample with setpoint frequency and record data simultaneously.

Step 102): system calibrating is calibrated: calibrated sensor pose and servomechanism installation systematic parameter at zero point by three-coordinates measuring machine, and completion system is demarcated;

Step 103): scanning workpiece, obtain data message: drive guide rail to move with known speed, simultaneously 3 2D laser scanners are treated sandblasting workpiece with setpoint frequency and are carried out scanning, sampling, guarantee treats that sandblasting workpiece is complete by laser sampling plane, and what record that 3 2D laser scanners collect take time as the laser measurement values data message of label.

As shown in Figure 4, described second step comprises the following steps:

Step 201) put cloud conversion and splicing: the reference frame setting up sand blasting machine people, by step 103) the laser measurement values data message that obtains, by the relative pose relation of time tag and sensor measurement polar coordinate system and reference frame, be converted to the cloud data under sand blasting machine people reference frame, and by all Point-clouds Registrations to together, obtain the part model be made up of cloud data under reference frame;

Step 202) some cloud filtering: for step 201) part model that obtains, carry out filtering process, obtain accurate workpiece point cloud model; Step 202) specifically comprise:

Step 2021) position of installing according to AGV dolly and range of movement, reject and treat the sample area that sandblasting workpiece is irrelevant, under obtaining sand blasting machine people reference frame, be with noisy workpiece point cloud model;

Step 2022) reject step 2021 by median filtering algorithm) workpiece point cloud model in noise spot: to step 2021) each data point p in the band noisy workpiece point cloud model that obtains _i, with p _ifor median window center, getting the median window length of side is w, then ask for intermediate value to the scan-data of the w × w in median window when time, when time, p _iremain unchanged; Wherein, δ represents median filter filtering threshold; Thus the accurate workpiece point cloud model under obtaining robot reference's coordinate system.

Step 203) some cloud smoothing processing: for step 202) the Accurate Points cloud model that obtains, due to the uncertainty of workpiece in sampling process with guide rail movement and the uncertainty of sensor, there is certain uncertainty in the surface points cloud model obtained, its performance is exactly that some cloud is level and smooth not.To this, the present embodiment adopts smoothing to a cloud based on the curved surface fitting method of Moving Least, and the scanning errors problem that move to remove guide rail, sensor accuracy etc. is brought, obtains accurate curve surface of workpiece point cloud model.

Adopt moving least squares surfaces approximating method, for step 202) the accurate workpiece point cloud model that obtains, smoothing process, obtains level and smooth point cloud model.Step 203) specifically comprise:

Step 2031) by step 202) the point cloud model region gridding that obtains;

Step 2032) revise the coordinate of each net point: the range of influence size first determining net point, then determine the point (x being positioned at net point range of influence _i, y _i, z _i), I=1,2 ..., n, n to represent in net point range of influence the sum of point; Fitting function subsequently according to formula (1) draws revised net point coordinate:

Z=f (x, y)=p ^t(x, y) α (x, y) formula (1)

In formula, p (x, y)=[1, x, y] ^trepresent linear base, subscript T represents transposition, and α (x, y) represents coefficient vector, and α (x, y) is according to optimization method obtain minimal value to try to achieve;

Step 2033) connection network lattice point, form fitting surface: according to revised net point coordinate connection network lattice point, form fitting surface;

Step 2034) cloud is projected to step 2033) fitting surface on, obtain level and smooth point cloud model.

Step 204) build STL model: adopt greedy projected triangle method to step 203) the level and smooth point cloud model that obtains processes, and generates the STL model of curve surface of workpiece.As shown in Figure 5, step 204) specifically comprise:

Step 2041) appoint and get a plane, using step 203) the some cloud that obtains as original point cloud, project to this plane, obtain and the planar point cloud one to one of the point in original point cloud; In Fig. 5, original point cloud p ₁, p ₂, p ₃, p ₄, p ₅, p ₆and p ₇, corresponding planar point cloud is p ' ₁, p ' ₂, p ' ₃, p ' ₄, p ' ₅, p ' ₆with p ' ₇;

Step 2042) for step 2041) the planar point cloud that obtains, it is that a sample triangular plate is as initial surface that random selecting three points connect, adopt algorithm of region growing constantly to merge to expand surface boundary triangular plate, form complete triangle mesh curved surface;

Step 2043) according to the annexation of point cloud projection, adopt the Topology connection that back projection method is determined between each initial three-dimensional point, gained triangle gridding is rebuild the surface mesh model obtained; Triangle gridding first space original point is projected to a plane, obtains plane projection triangular mesh, then carries out back projection according to the one-to-one relationship of projection, obtain the triangle gridding of space original point;

Step 2044) by step 2043) the surface mesh model that generates stores according to stl file format standard, obtains the STL digital-to-analogue model of workpiece.

As shown in Figure 6, the 3rd described step comprises the following steps:

Step 301) segmentation of areal model point cloud: to step 203) the level and smooth point cloud model that obtains, adopt and split based on stochastic sampling conforming some cloud partitioning algorithm, setting parted pattern is areal model, the minimal amount of model intra-office point and algorithm permissible variation distance absolute value, and segmentation obtains the fitting parameter of one group of plane point set set be made up of surface of the work Different Plane point set and each plane point set.As preference, the minimal amount of model intra-office point is 20, and algorithm permissible variation distance absolute value is 1cm.

For step 203) the level and smooth point cloud model that obtains, form is as follows:

ax+by+cz+d＝0

Wherein, (x, y, z) represents the three-dimensional coordinate of point, and a, b, c, d are plane fitting parameters; Adopt and split based on stochastic sampling conforming some cloud partitioning algorithm, setting parted pattern is areal model, and algorithm operational factor arranges as follows: model intra-office point minimal amount is 20, and algorithm permissible variation distance absolute value is 1cm.Final segmentation obtains some fit Plane point set S _i(i=1,2 ..., N) and corresponding fitted model parameters a _i, b _i, c _i, d _i.

Sampling consistency algorithm is prior art.The described process carrying out splitting based on stochastic sampling conforming some cloud partitioning algorithm is:

3011) the some points of Stochastic choice are concentrated from the cloud data of input, and Calculation Plane model parameter.Current most imperial palace point number is set to dm=0;

3012) arrange distance threshold to this cloud data collection, this point a little, if the distance putting fit Plane is less than threshold value, is then classified as interior point, otherwise is exterior point by the institute that test data is concentrated one by one;

3013) the number d1 of this interior point of statistics, judges whether the number threshold value d0 being greater than setting, if so, performs step 3014), if not, direct redirect performs step 3015);

3014) by interior some fit Plane again, export, store all interior points as segmentation result as model, segmentation terminates;

3015) d1 and dm is compared, if d1>dm, store the areal model of this step matching, and dm=d1 is set;

3015) contrast with current maximum intra-office point number, if be greater than, replaced current maximum intra-office point number, and store current model coefficient, return step 3011), until segmentation terminates.

Step 302) detect inner and outer boundary key point: step 302) specifically comprise: by step 301) each plane point set S of obtaining _iplane fitting parameters according to its correspondence is handled as follows:

Step 3021) projection of some cloud: by plane point set S _iin the plane that represents to fitting parameter of all spot projections in, obtain the agonic planar point cloud model of this plane point set;

Step 3022) detect inside and outside packet boundary: the inner and outer boundary key point arrangement set extracting some cloud: for the cloud data in each planar point cloud model, choose the minimum outsourcing polygon vertex of plane respectively as key point: be polygon outer boundary summit situation for key point, with planar process vector direction for top, with one group of clockwise key point sequence composition border key point; Be polygon inner boundary summit situation for key point, with planar process vector direction for top, with one group of counterclockwise key point sequence composition border key point.Key point is polygon angle point, and by each 1 the flanking sequence point of this point and front and back, whether conllinear obtains.

Step 303) simplify frontier point: to step 302) the key point sequence that obtains simplifies, extracts angle point as key point, reject non-angle point element in sequence, the boundary point sequence set be simplified;

Step 304) carry out STL semantic label: according to step 303) the boundary point sequence set of simplification that obtains is to step 2044) the STL digital-to-analogue model that generates carries out Region dividing, in STL digital-to-analogue model, mark the inner and outer boundary in sand region to be painted, realize the semantic label of STL digital-to-analogue model.

As shown in Figure 9, the 4th step comprises the following steps:

Step 401) extraction model information: the STL model generated according to the 3rd step, extracts triangular plate grid information.

Step 402) build bounding box: build a rectangular parallelepiped that the STL grid surface of workpiece can be included as bounding box, and create corresponding bounding box coordinate system, the initial point of bounding box coordinate system is in the geometric center of bounding box rectangular parallelepiped, and each coordinate axis is parallel with each limit of rectangular parallelepiped.

The construction process of bounding box as shown in Figure 7a, by the initial point O of bounding box coordinate system _bOXbe set in the geometric center of bounding box rectangular parallelepiped, the coordinate axis of bounding box coordinate system is parallel with each limit of rectangular parallelepiped, and establishes and axle x _bOXthe parallel length of side is A, with axle y _bOXthe parallel length of side is B, with axle z _bOXthe parallel length of side is C.As long as obtain an O _bOX, vector of unit length x _bOX, y _bOX, z _bOX, and length of side A, B, C, just can determine pose and the size of bounding box.

As shown in Figure 7b, if total N number of triangle gridding sheet, wherein three summits of i-th triangle gridding sheet are respectively p ⁱ, q ⁱ, r ⁱ, area is A ⁱ, triangle barycenter is O ⁱ(i=1,2 ..., N).If the total area of N number of triangle gridding sheet is A ^h, then the geometric center point O of bounding box rectangular parallelepiped _bOXcoordinate figure in workpiece coordinate system is each triangle gridding sheet barycenter average μ of the Area-weighted of coordinate figure in workpiece coordinate system, can be drawn by following formula:

$O_{BOX}=\mathrm{\μ}=\underset{i=1}{\overset{N}{\Σ}}\left(A^i{O}^i\right)/\underset{i=1}{\overset{N}{\Σ}}{A}^i=\underset{i=1}{\overset{N}{\Σ}}\left(A^i{O}^i\right)/A^H$

If the covariance matrix on each summit of triangle gridding sheet is C, the Elements C of 3 × 3 Matrix C jth row, kth row _jktried to achieve by following formula:

$C_{jk}=\underset{i=1}{\overset{N}{\Σ}}\frac{A^i}{12A^H}(9O_j^i{O}_k^i+p_j^i{p}_k^i+q_j^i{q}_k^i+r_j^i{r}_k^i)-{\mathrm{\μ}}_j{\mathrm{\μ}}_k,1\≤j,k\≤3$

Wherein, $O^i={(O_1^i,O_2^i,O_3^i)}^T,p^i={(p_1^i,p_2^i,p_3^i)}^T,q^i={(q_1^i,q_2^i,q_3^i)}^T,r^i={(r_1^i,r_2^i,r_3^i)}^T,$ μ＝(μ ₁,μ ₂,μ ₃) ^T。

Because covariance matrix C is real symmetric matrix, the proper vector corresponding to different characteristic value is orthogonal, obtains the proper vector that Matrix C three is mutually orthogonal, namely obtains the direction vector of bounding box coordinate system coordinate axis after unitization.Then all triangle gridding sheet summits are traveled through, obtain the projection maximal value of each summit in three coordinate axis and minimum value, be respectively x _max, x _min, y _max, y _min, z _max, z _min, thus determine the length of side of bounding box: a=x _max-x _min, b=y _max-y _min, c=z _max-z _min.

Step 403) choose sandblasting feature frame: STL grid surface is projected to the face perpendicular to each axle positive dirction of bounding box, calculates the area of each projection, and choose the feature frame of a maximum face of projected area as sandblasting.In bounding box coordinate system, if sprayed surface is A along the projected area of x-axis positive dirction _x+, the projected area along y-axis positive dirction is A _y+, the projected area along z-axis positive dirction is A _z+.A _x+, A _y+, A _z+middle numerical value the maximum, selects the bounding box surface corresponding to it as the spray characteristics frame of system.

Step 404) generate sandblasting characteristic curve: as shown in Figure 8, if sandblasting covering radius is r, the spacing of each for sandblasting path stroke is chosen as r/2, the distance between adjacent feature line, thus on characteristic face, generates the sandblasting characteristic curve be parallel to each other.

Step 405) generate sandblasting track: project at surface of the work along normal direction with characteristic curve, the curve intercepted is sandblasting stroke, is connected by adjacent sandblasting stroke, obtains final sandblasting track.

2D laser scanner can gather two-dimensional distance information, and insensitive to light intensity, is applicable to measuring depth information, but makes problem become complicated because it cannot obtain 3 D stereo depth information.In view of sandblasting engineering only needs the feature obtaining part model, by scanning the workpiece of advancing by special exercise rule with multiple fixing 2D laser scanner, 3 dimension point cloud models of workpiece can be calculated, and then sand blasting machine people automatic path generation method can be solved.

The sand blasting machine people automatic path generation method based on line laser structured light of the embodiment of the present invention, the industrial 2D laser scanner workpiece be opposite on AGV dolly being first fixed on ad-hoc location by 3 carries out scanning and realizes line laser structured light data acquisition; Next carries out surface of the work modeling, by steps such as a cloud conversion and splicing, the filtering of some cloud, some cloud smoothing processing, STL digital-to-analogue structures, and final acquisition STL digital-to-analogue; Then extraction model geometry and topological characteristic, mainly refers to plane characteristic and Porous Characteristic, and then according to the characteristic information extracted, curved surface is divided into some planes not with cavity; Last according to STL model construction feature frame, adopt cutting planes projecting method to realize automatic sand blasting Track Pick-up.The sand blasting machine people automatic path generation method of the embodiment of the present invention is carried out at line sweep surface of the work by low cost 2D laser sensor, to set up 3D digital-to-analogue comparatively accurately, adopt the optimization movement locus of the automatic plane-generating robot of the mode of online programming on this basis, abandon traditional artificial teach programming mode, automatically surface tracks is generated in the mode of online programming, and reach the object of all standing processing, simply efficiently.

The method of the embodiment of the present invention realizes mainly comprising 2D line laser structured light and carries out workpiece modeling and the automatic sand blasting coordinates measurement two large divisions based on built part model, its advantage major embodiment in the following areas:

First, the first step and second step can generate workpiece STL model fast by the 2D line laser structured light of low cost.Compared to the 3D laser scanner that reverse modeling is conventional, the 2D line sweep laser that the embodiment of the present invention adopts is under the prerequisite ensureing specific blasting craft precision, greatly can reduce hardware cost, and the data handling procedure of 2D line laser structured light is more quick than 3D laser stereo lithography process, the real-time online modeling of workpiece can be realized, thus substantially increase applicable surface and the ease for use of this method.

Secondly, the method in the STL auto-building model sandblasting path by generation in real time that the embodiment of the present invention proposes, compared to traditional artificial teaching operation mode, lengthy and tedious artificial teaching process can be avoided, substantially reduce the integral production time, and improve automated job level and the production efficiency of sandblasting industry.And compared with the off-line programing mode of routine, the present invention realizes without the need to workpiece cad model, off-line programing can be solved and depend on the defect of accurate CAD digital-to-analogue (for most of domestic process, often be difficult in advance obtain accurate digital-to-analogue), and can realize carrying out the optimizing process such as on-line tuning and automatic deviation correction according to real time laser scan-data, wide accommodation, dirigibility is strong, is particularly suitable for the occasion of short run, multi items, non-standard workpiece.

On the whole, the embodiment of the present invention is by the online sandblasting path generating method based on 2D low cost line sweep laser, with low cost, efficiently simple to operate, without the need to carrying out loaded down with trivial details teaching process, overcome the defect of Traditional Man teach mode production cycle length, very flexible, also compensate for the deficiency that conventional offline programming needs the original CAD drawing of workpiece simultaneously, the processing of especially applicable short run, multi items, nonstandard product and manufacture process.

Claims (9)

1., based on a sand blasting machine people automatic path generation method for line laser structured light, it is characterized in that: this generation method comprises the following steps:

The first step: obtain workpiece data information: adopt 2D laser scanning methods to obtain the scanning sample point data information treating sandblasting surface of the work;

Second step: set up surface of the work STL model: by point cloud pretreatment, sets up and treats sandblasting surface of the work STL model;

3rd step: divide curved surface: extract and utilize geometric properties and the topological characteristic of surface of the work STL model, is divided into some not with empty plane by curve surface of workpiece;

4th step: generate sandblasting track: according to surface of the work STL model construction feature frame, adopts cutting planes projecting method, generates sandblasting track.

2., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 1, it is characterized in that: the described first step comprises the following steps:

Step 101): arrange sand-blast shop: be placed in the middle part of workshop by AGV dolly, 3 industrial 2D laser scanners are fixedly mounted on support respectively, and 3 industrial 2D laser scanners lay respectively at top and two sides of AGV dolly, to treat that sandblasting workpiece is placed on AGV dolly, treat that sandblasting workpiece and AGV dolly are synchronized with the movement with guide rail;

Step 102): system calibrating is calibrated: calibrated sensor pose and servomechanism installation systematic parameter at zero point by three-coordinates measuring machine, and completion system is demarcated;

Step 103): scanning workpiece, obtain data message: drive guide rail to move with known speed, simultaneously 3 2D laser scanners are treated sandblasting workpiece with setpoint frequency and are carried out scanning, sampling, guarantee treats that sandblasting workpiece is complete by laser sampling plane, and what record that 3 2D laser scanners collect take time as the laser measurement values data message of label.

3., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 1, it is characterized in that: described second step comprises the following steps:

Step 201) put cloud conversion and splicing: the reference frame setting up sand blasting machine people, by step 103) the laser measurement values data message that obtains, by the relative pose relation of time tag and sensor measurement polar coordinate system and reference frame, be converted to the cloud data under sand blasting machine people reference frame, and by all Point-clouds Registrations to together, obtain the part model be made up of cloud data under reference frame;

Step 202) some cloud filtering: for step 201) part model that obtains, carry out filtering process, obtain accurate workpiece point cloud model:

Step 203) some cloud smoothing processing: adopt moving least squares surfaces approximating method, for step 202) the accurate workpiece point cloud model that obtains, smoothing process, obtains level and smooth point cloud model;

Step 204) build STL model: adopt greedy projected triangle method to step 203) the level and smooth point cloud model that obtains processes, and generates the STL model of curve surface of workpiece.

4., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 3, it is characterized in that: described step 202) specifically comprise:

Step 2021) position of installing according to AGV dolly and range of movement, reject and treat the sample area that sandblasting workpiece is irrelevant, under obtaining sand blasting machine people reference frame, be with noisy workpiece point cloud model;

Step 2022) reject step 2021 by median filtering algorithm) workpiece point cloud model in noise spot: to step 2021) each data point p in the band noisy workpiece point cloud model that obtains _i, with p _ifor median window center, getting the median window length of side is w, then ask for intermediate value to the scan-data of the w × w in median window when time, when time, p _iremain unchanged; Wherein, δ represents median filter filtering threshold; Thus the accurate workpiece point cloud model under obtaining robot reference's coordinate system.

5., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 3, it is characterized in that: described step 203) specifically comprise:

Step 2031) by step 202) the point cloud model region gridding that obtains;

Step 2032) revise the coordinate of each net point: the range of influence size first determining net point, then determine the point (x being positioned at net point range of influence _i, y _i, z _i), I=1,2, n, n to represent in net point range of influence the sum of point; Fitting function subsequently according to formula (1) draws revised net point coordinate:

Z=f (x, y)=p ^t(x, y) α (x, y) formula (1)

In formula, p (x, y)=[1, x, y] ^trepresent linear base, subscript T represents transposition, and α (x, y) represents coefficient vector, and α (x, y) is according to optimization method $J=\underset{I=1}{\overset{n}{\Σ}}(x-x_I)\[p^T(x_I,y_I)\mathrm{\α}(x,y)-z_I\]$ Obtain minimal value to try to achieve;

Step 2033) connection network lattice point, form fitting surface: according to revised net point coordinate connection network lattice point, form fitting surface;

Step 2034) cloud is projected to step 2033) fitting surface on, obtain level and smooth point cloud model.

6., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 3, it is characterized in that: described step 204) specifically comprise:

Step 2041) appoint and get a plane, using step 203) the some cloud that obtains as original point cloud, project to this plane, obtain and the planar point cloud one to one of the point in original point cloud;

Step 2042) for step 2041) the planar point cloud that obtains, it is that a sample triangular plate is as initial surface that random selecting three points connect, adopt algorithm of region growing constantly to merge to expand surface boundary triangular plate, form complete triangle mesh curved surface;

Step 2043) according to the annexation of point cloud projection, adopt the Topology connection that back projection method is determined between each initial three-dimensional point, gained triangle gridding is rebuild the surface mesh model obtained;

Step 2044) by step 2043) the surface mesh model that generates stores according to stl file format standard, obtains the STL digital-to-analogue model of workpiece.

7., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 1, it is characterized in that: the 3rd described step comprises the following steps:

Step 301) segmentation of areal model point cloud: to step 203) the level and smooth point cloud model that obtains, adopt and split based on stochastic sampling conforming some cloud partitioning algorithm, setting parted pattern is areal model, and segmentation obtains the fitting parameter of one group of plane point set set be made up of surface of the work Different Plane point set and each plane point set;

Step 302) detect inner and outer boundary key point;

Step 303) simplify frontier point: to step 302) the key point sequence that obtains simplifies, extracts angle point as key point, reject non-angle point element in sequence, the boundary point sequence set be simplified;

Step 304) carry out STL semantic label: according to step 303) the boundary point sequence set of simplification that obtains is to step 2044) the STL digital-to-analogue model that generates carries out Region dividing, in STL digital-to-analogue model, mark the inner and outer boundary in sand region to be painted, realize the semantic label of STL digital-to-analogue model.

8., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 7, it is characterized in that: described step 302) specifically comprise: by step 301) each plane point set S of obtaining _iplane fitting parameters according to its correspondence is handled as follows:

Step 3021) projection of some cloud: by plane point set S _iin the plane that represents to fitting parameter of all spot projections in, obtain the agonic planar point cloud model of this plane point set;

Step 3022) detect inside and outside packet boundary: the inner and outer boundary key point arrangement set extracting some cloud: for the cloud data in each planar point cloud model, choose the minimum outsourcing polygon vertex of plane respectively as key point: be polygon outer boundary summit situation for key point, with planar process vector direction for top, with one group of clockwise key point sequence composition border key point; Be polygon inner boundary summit situation for key point, with planar process vector direction for top, with one group of counterclockwise key point sequence composition border key point.

9., according to the sand blasting machine people automatic path generation method based on line laser structured light according to claim 1, it is characterized in that: the 4th described step comprises the following steps:

Step 401) extraction model information: the STL model generated according to the 3rd step, extracts triangular plate grid information;

Step 402) build bounding box: build a rectangular parallelepiped that the STL grid surface of workpiece can be included as bounding box, and create corresponding bounding box coordinate system, the initial point of bounding box coordinate system is in the geometric center of bounding box rectangular parallelepiped, and each coordinate axis is parallel with each limit of rectangular parallelepiped;

Step 403) choose sandblasting feature frame: STL grid surface is projected to the face perpendicular to each axle positive dirction of bounding box, calculates the area of each projection, and choose the feature frame of a maximum face of projected area as sandblasting;

Step 404) generate sandblasting characteristic curve: set sandblasting covering radius as r, the spacing of each for sandblasting path stroke is chosen as r/2, the distance between adjacent feature line, thus on characteristic face, generate the sandblasting characteristic curve be parallel to each other;

Step 405) generate sandblasting track: project at surface of the work along normal direction with characteristic curve, the curve intercepted is sandblasting stroke, is connected by adjacent sandblasting stroke, obtains final sandblasting track.